There has been an inorganic board containing a hydraulic inorganic material such as a cement, and a woody reinforcing material such as a pulp as main components. This inorganic board has a high specific gravity and a good freezing thawing resistance. However, in the case of adding plenty of pulp thereto in order to increase a bending strength, incombustibility is lowered and freezing thawing resistance is deteriorated. Also as an inorganic board with high specific gravity is hard, which causes constructability (such as easiness in putting in a nail) to become worse. In view of this, a variety of lightweight materials have tried to be added thereto. For example, JP Patent 3374515 discloses a cement molding material containing a vermiculite and JP kokoku (examined patent application publication) 08-32603 discloses an addition of a fly ash and/or a spherical calcium silicate.